The present invention relates to glossable developer compositions of the type which are useful in recording materials such as carbonless paper and photographic materials employing encapsulated photosensitive compositions where they function as electron acceptors and react with substantially colorless electron donating compounds to produce a visible image.
Prolonged exposure of phenolic developers to heat and/or sunlight results in degradation of the developer. When phenolic developers are used on a developer sheet, such degradation is accompanied by yellowing. This reduces the commercial value of the recording system. Attempts have been made to reduce the tendency for phenolic developers to yellow for this reason.
U.S. Pat. Nos. 4,260,179; 4,262,938; and 4,296,948 teach the addition of zinc oxide and titanium dioxide to reduce yellowing in developer sheets.
Japanese Published Application 78/9359 discloses a developer composition for pressure-sensitive copy paper comprising 100 parts of a phenol-formaldehyde polymer, a disubstituted phenol and a hydroxyphenylbenzotriazole compound.